In a large soup pot set over medium heat, warm the olive oil. Mince 1 of the garlic cloves and add it to the pot with the onion, sage and a pinch of salt. Cook, stirring often to prevent browning, until the onion has softened, about 3 minutes. Add the tomatoes, along with any juices and seeds, and 1 teaspoon of salt.

Cut one-third of the bread into slices measuring about ⅓ inch thick and set aside (you’ll be making croutons with those in a moment). Cut the remaining bread into rough cubes and add them to the pot. Pour in the stock, bring to a simmer, cover and cook until the tomatoes and bread are very soft, 20 to 25 minutes.

Meanwhile, toast the reserved slices of bread. Cut the remaining garlic clove in half and, while the bread is still warm, rub both sides with the cut side of the halved garlic clove. Dice the bread into ¼-inch pieces to make croutons.

When the soup is done, add a few dashes of hot sauce to it, then taste and adjust the seasoning. Divide the soup among 4 to 6 bowls. Season with the black pepper and top with the reserved croutons and tarragon. Serve immediately.